1. Field of the Invention
The present invention relates to communication navigation systems and methods, etc. for performing navigation by transmitting map data to navigation terminals via a communication network. More particularly, the invention is directed to a communication-efficient communication navigation system and method, etc.
2. Description of Related Art
Various types of navigation systems have been proposed, which perform navigation by transmitting map data and route guidance information from a server, via computer and mobile communications networks including the Internet, to various types of navigation terminals, such as in-vehicle navigation units, portable navigation units, PDAs (Personal Digital Assistants) and cellular telephones, according to their request. Each of these navigation terminals presents a user with predetermined information visibly and audibly, based on position data detected by a GPS (Global Positioning System) receiver mounted thereon as well as map data and route guidance information transmitted from the server, to guide the user to his or her destination.
In these communication navigation systems, the route guidance information transmitted from the server plays an important role in guiding the user to his or her destination, together with the map data. However, each navigation terminal accepts only a type of route guidance information which is uniquely compatible with itself. If the server sends all types of guidance data to each of all the navigation terminals, the server must handle a vast volume of data for transmission to increase its transmission cost and time.